1. Field of the Invention
The present invention relates to an electric control apparatus for an industrial robot the arm of which is actuated to carry out machining of a workpiece by means of a machining tool attached thereto.
2. Description of the Prior Art
An electric control apparatus for an industrial robot of this kind includes memory means for memorizing a plurality of teaching points representing the contour of a workpiece to be machined and execution means for operating the robot in such a manner that a machining tool attached to the robot's arm is moved along a teaching line defined by the teaching points to remove burrs from the workpiece or to polish the workpiece. In the case that an end milling tool is attached to the robot's arm to remove burrs from the workpiece, there will occur relative displacement between the tool and the workpiece due to machining reaction force acting on the robot, the workpiece support and the like. Since the machining reaction force varies with greatness in size or extent of burrs, the actual machining line will differ from the teaching line, resulting in an increase of unremoved burrs on the workpiece. For the purpose of reducing such unremoved burrs, it has been considered to detect a load acting on a servomotor of the tool for decreasing the moving speed of the tool in accordance with an increase of the load and for increasing the moving speed of the tool in accordance with a decrease of the load. In such control of the tool, it is impossible to remove partly remained burrs from the workpiece due to a delay of time in operation of the load detector and in a control system of the robot.